Multi-Radio Access Technology Paging

ABSTRACT

Systems and methods for improved paging are described. In one embodiment, a method is described, comprising: providing a combined database in a heterogeneous radio access network at a coordinating gateway between a plurality of radio access network nodes and a plurality of core network nodes; at the coordinating gateway, storing a first location of a user device in the combined database in association with a user device identifier and based on receiving a first user device registration request at a first radio access network; at the coordinating gateway, storing a second location of the user device in the combined database in association with the user device identifier and based on receiving a second user device registration request at a second radio access network; and querying the combined database for a last known location of the user device across both the first and the second radio access network.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 62/382,354, entitled “Multi-Radio Access Technology Paging,” filed on Sep. 1, 2016, the entire contents of which are hereby incorporated by reference for all purposes. In addition, this application incorporates the following documents by reference in their entirety: U.S. Patent Publication No. US20140133456A1, entitled “Dynamic Multi-Access Wireless Network Virtualization,” filed on Sep. 23, 2013; U.S. Patent Publication No. US20140092765A1, entitled “Heterogeneous Self-Organizing Network for Access and Backhaul,” and filed on Sep. 12, 2013; U.S. Patent Publication No. US20140126410A1, entitled “Heterogeneous Self-Organizing Network for Access and Backhaul,” and filed on Jan. 3, 2014; U.S. Patent Publication No. US20150173111A1, entitled “Virtualization of the Evolved Packet Core to Create a Local EPC,” filed on Dec. 15, 2014; U.S. Patent Publication No. US20160029246A1, entitled “Signaling Storm Reduction from Radio Networks,” filed on Jul. 22, 2015; U.S. Patent Publication No. US20160044531A1, entitled “Congestion and Overload Reduction,” filed on Aug. 10, 2015; and U.S. Patent Publication No. US20160128020A1, entitled “Tracking Area Planning,” filed on Nov. 2, 2015. In addition, 3GPP TS 23.003 v. 13.5.0, dated Mar. 17, 2016, is also hereby incorporated by reference in its entirety for all purposes.

BACKGROUND

A user equipment (UE) enters into an idle mode when its radio connection is released. Once in idle mode, if the UE needs to be reached by the network, the 3G and LTE standards define a procedure called paging. Paging involves broadcasting the UEs identity in the radio cells belonging to a set of eNodeBs or base stations grouped into tracking areas. Paging Messages are broadcasted over the location area code (LAC) for UMTS, routing area code (RAC) for GERAN, and tracking area code (TAC) for LTE area so that a Mobile Terminating Call may be answered. If the UE is present in one of the cells, it will respond to paging by performing a service request procedure. This results in the radio connection being re-established and the network becoming able to communicate with the UE for either control or data traffic.

Since many UEs in the LTE network are in idle mode at any given time, this equates to a high number of paging attempts going on a given network. A paging strategy is needed to reach the UE while reducing load and effectively utilizing paging resources.

SUMMARY

Systems and methods for improved paging are described. In a first embodiment, a method may be disclosed, comprising: providing a combined user device location database in a heterogeneous radio access network at a coordinating gateway between a plurality of radio access network nodes and a plurality of core network nodes; at the coordinating gateway, storing a first location of a user device in the combined user device location database in association with a user device identifier and based on receiving a first user device registration request at a first radio access network; at the coordinating gateway, storing a second location of the user device in the combined user device location database in association with the user device identifier and based on receiving a second user device registration request at a second radio access network; and querying the combined user device location database for a last known location of the user device across both the first and the second radio access network, thereby maintaining a combined user device location database across multiple radio access technologies in a heterogeneous radio access network.

The user device may be a UE, and the user device identifier may be an international mobile subscriber identity (IMSI). The first and second radio access network provide access via different radio access technologies. The method may further comprise sending a paging request to the user device via the first radio access network based on the last known location. The method may further comprise receiving a paging request to the user device using a first radio access technology of the first radio access network. The method may further comprise recording an international mobile subscriber identity (IMSI) of the user device at the coordinating gateway from both the first and the second received user device registration requests. The coordinating gateway may be an evolved packet data gateway (ePDG) or trusted wireless access gateway (TWAG), and the method further comprises recording an international mobile subscriber identity (IMSI) of the user device upon IPsec security tunnel establishment for the user device at the coordinating gateway. The coordinating gateway may be an evolved packet data gateway (ePDG) or trusted wireless access gateway (TWAG), and the coordinating gateway may be a gateway between the plurality of radio access network nodes and a Long Term Evolution (LTE) packet data network gateway (PGW), and the coordinating gateway may be a gateway between the plurality of radio access network nodes and a serving global packet radio service support node (SGSN).

The method may further comprise receiving an incoming paging request for a first radio access technology, and based on the queried last known location, preferentially sending a paging request to a multi-radio access technology base station. The first location and the second location may be base station identifiers. The first location may be an identifier of the first radio access network and the second location may be an identifier of the second radio access network, and the first location and the second location may be E-UTRAN cell global identifiers (ECGIs). The method may further comprise storing position coordinates of the user device in the combined user device location database, retrieving the stored position coordinates of the user device as a result to a query to the combined user location database for the last known location of the user device, and sending paging messages to base stations in a geographical region based on the retrieved stored position coordinates.

In a second embodiment, a system for providing paging in a cellular telecommunications network may be disclosed, comprising: a first multi-radio access technology (multi-RAT) base station; a second multi-RAT base station in communication with the first multi-RAT base station; and a coordinating gateway in communication with the first and second multi-RAT base stations and situated between the first and second multi-RAT base stations and a core network, the coordinating gateway The method may further comprise: a combined user device location database, and a processing module configured to perform steps including: providing a combined user device location database in a heterogeneous radio access network at the coordinating gateway between the first and second multi-RAT base stations and a plurality of core network nodes; at the coordinating gateway, storing a first location of a user device based on receiving a first user device registration request at the first multi-RAT base station; at the coordinating gateway, storing a second location of the user device based on receiving a second user device registration request at the second multi-RAT base station; and querying the combined user device location database for a last known location of the user device across both the first and the second multi-RAT base stations, thereby maintaining a combined user device location database across multiple radio access technologies in a heterogeneous radio access network.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a call flow diagram of a typical paging procedure in the prior art.

FIG. 2 is a schematic diagram of a deployment architecture for a wireless network, in accordance with some embodiments.

FIG. 3 is an exemplary call flow diagram showing improved paging.

FIG. 4 is a schematic diagram of a mesh network node, in accordance with some embodiments.

FIG. 5 is a schematic diagram of a routing coordination node, in accordance with some embodiments.

DETAILED DESCRIPTION

In small cell technologies, consider the case where there are thousands of such Paging request messages and all of these need to be broadcasted. As many small-cells share the same CN-side LAC, RAC and TAC values, the Paging flooding would unnecessarily load the whole networks of small-cells.

Hence, there was a need of the optimization techniques for the paging. Such Paging messages could be optimized to be sent to a selective number of small-cells instead of flooding it over entire small-cells network.

Technologies for paging optimization exist, but very little material is available for the Paging Optimization across the multi-RAT heterogeneous network gateways.

Heterogeneous network (HetNet) gateways have a centralized entity for controlling multi-RAT access technologies. UE permanent identity information received from one RAT-technology can be stored along with multi-RAT cell-identifier, updated and mapped for other RAT-technologies. When there is an incoming Paging for one technology, based on the past UE-entry stored information, the Paging Request could be directed to the multi-RAT cell first. The position coordinates of the UE could be additionally stored in the mapping table, and the Paging message could be sent to the multi-RAT cells in that geographical region.

The tradeoff is that we have to maintain a centralized UE-database at HetNet gateway which could be queried and updated across multiple Access-technologies.

Parallel Wireless has a distinction of supporting 3G, LTE, WiFi and SON on same box and thus, sharing the global information like UE-database across multi-access technologies and achieving Paging optimization. This solution may be generalized for any heterogeneous solution supporting 3G, LTE, WiFi, etc.

The following describes the case of HetNet Gateway supporting the Wi-Fi (ePDG, TWAG), LTE and 3G technologies. A typical UE after finishing a 3G CS-Call/PS-Data or after doing the location-Update moves to Idle-Mode. Such Idle-UE may move to another coverage zone with the same Location/Routing-Area Code and hence, the exact location of UE will not be known to the Core-networks. Such UE when comes to a Wi-Fi Coverage shall create association with the Wi-Fi-Access Point and get connected to Internet via Wi-Fi. Hence, Core-network entities like MSC, SGSN or even MME may not be aware of the exact location of that UE. If there is any incoming 3G CS-Paging for such UE at HNBGW, then the Paging message shall be broadcasted to many Small-cells registered with the same Location-Area-code. Even there is a possibility that such LTE PS-Paging shall be broadcasted on tracking area level.

When a UE establishes IPSEC connection using IKE-v2 with Wi-Fi-Gateway like ePDG, during IKE-v2 Auth phase, UE publishes its IMSI or TMSI in the UE-Id field. The HetNet Gateway (HNG) may update this UE information like IMSI in its database. Such entry may store the CWS-information, UE-Ids like IMSI, and TMSI per Entry.

When HNG receives any CS or PS-Paging from MSC or SGSN for an incoming CS or PS-call respectively, it may refer the update IMSI-database and page the UE to the zone where the UE is attached with Wi-Fi. With this approach, Paging Optimization could be achieved at HNG by Paging the Zone where the UE was last seen. Please refer the figure for more details.

Similarly, in case of LTE and 3G Multi-RAT system, the UE-Permanent Identity information received from LTE can be used for selectively paging the UE during CS-Paging from the MSC if there is no CS-FB feature support at the EPC.

In 4G, subscriber's IMSI is not always known. But in 3G subscriber's IMSI is always known. We can use 3G's paging cache to forward 4G's IMSI based paging messages. When the core network pages the UE, it requires the UE to respond in respective RAT. At co-ordinating gateway (i.e. HNG), we can use the multi-RAT UE database to narrow down the paging to one or more CWS where the UE was last seen. This helps reduce the paging load on the overall network and makes the procedure more efficient. As well, in some embodiments, the present disclosure combines LTE paging, circuit-switched connection paging, Wi-Fi paging (with ePDG or TWAG), and 3G paging into a single cohesive solution.

We want to make use of CWS-identity which is common for 3G, 4G and wifi and thus, when the UE attaches via one RAT, we know the IMSI, other UE-identifiers and CWS-identity and store in our combined database. Without this feature/idea, the UE would need to be paged in multiple cells belonging to one or multiple location/tracking areas. According to the disclosed systems and methods, a single RAT for the UE can be identified with high confidence, even across multiple RATs.

When there is Paging from other RAT technology with same IMSI, or other UE-identifiers, we will do the query in the Data-base to identify the last known CWS-identity for that UE and thus, the Location information. The UE-data-base was created from 1 Radio-Technology but is used for doing Paging optimization for other Radio-Technology. Now, we will forward Paging Request to that CWS. UE permanent identity information received from one RAT-technology can be stored along with multi-RAT cell-identifier, updated and mapped for other RAT-technologies.

FIG. 1 is a call flow diagram of a typical paging procedure in the prior art. Tracking area 1 is composed of multiple eNodeBs, as shown in the diagram at 101. As well, tracking areas 1 and 1 are composed of multiple eNodeBs at 102 and 103. At 104, a mobility management entity (MME) is shown. The MME is part of an operator core network, and is responsible for managing mobility and for performing paging of a UE when it is inactive and data is received for it at a serving gateway (SGW; not shown) in the core network. At 105, a packet core is shown. Packet core 105 represents the SGW, as well as other nodes in the core network, such as a packet gateway (PGW). Packet core 105 may be an evolved packet core (EPC).

At step 106, a downlink data notification is sent from the packet core 105 to MME 104. MME 104 acknowledges receipt of the downlink data notification at step 107. At this time, the MME must now find the UE via paging eNodeBs until the UE is found.

At step 108, the MME initiates paging. According to the LTE standard, the network keeps track of all UEs at a tracking area level, in order to facilitate paging. Therefore, the MME has information about the last known tracking area of the UE, which is TA 1 101. MME 104 thus pages the UE at TA 1. However, in the example illustrated, the UE is no longer nearby any of the base stations in TA 1.

At step 109, since the UE was not found in TA 1, MME 104 commences paging at TAs 1, 1, and 1. Multiple paging messages are sent out. The paging messages are very expensive from a network point of view, as these messages require each base station to send out a paging message and listen for responses, and as they require a great deal of signaling to be coordinated between the MME and every eNodeB in each affected tracking area. Paging messages are also expensive because, until they are stopped, they require the affected eNodeBs to repeatedly perform the paging procedure until the UE is found. Paging messages also require all UEs connected on the network to wake up to check to see whether it has been paged, draining UE battery.

At step 110, once the UE being paged receives the paging message and wakes up, the UE (not shown) responds by attaching to an eNodeB or otherwise sending a service request, and this service request is transmitted via the eNodeB up to the MME 104 and packet core 105. At step 111, the packet core connects the UE to network services, delivers the waiting data, and also causes paging to be stopped at all eNodeBs, at last ending the signaling load on the network.

FIGS. 2 and 3 which follow provide more information about the context of paging in the above system. The base stations described below may be multi-RAT base stations and may permit access or backhaul using a variety of combinations of radio access technologies.

FIG. 2 is a schematic diagram of a deployment architecture for a wireless network, in accordance with some embodiments. Box 201 includes a plurality of heterogeneous radio access networks (RANs) using different radio access technologies and located in different environments. Rural, enterprise, public access, and residential radio access nodes are shown, but additional heterogeneous network access nodes may be contemplated as well, such as base stations used in a military context, small cell/micro-cell/pico-cell/femto-cell deployments, and other deployments. This heterogeneous mix of RANs is shown in conjunction with one or more macro cells 202. Each of the heterogeneous RANs and the macro cells are managed by coordinating gateway 204, as explained further below.

Backhaul for the heterogeneous RAN sites and macro cells may also be provided, as shown at box 203. The backhaul connections may also be diverse and widely varied. For example, high-throughput, low-latency fiber, high-latency satellite, Ethernet, wireless backhaul such as microwave or non-line of sight, or other backhaul connections may be used, sometimes in conjunction with each other.

Box 204 shows a coordinating node, also identified here as a heterogeneous network gateway, or hetnet gateway. Coordinating node 204 is located in the cloud and may be at a remote site, but is located between the RAN and the core network and is in communication with both RAN 201, 202 and core network(s) 205. Coordinating node 204 sends and receives all data to and from RANs 201 and 202, and may be considered a gateway between the RAN and the core network. Coordinating node 204 includes evolved packet core (EPC) virtualization stack 204 a in communication with radio virtualization stack 204 b. Both virtualization stacks 204 a, 204 b provide back-to-back user agent (B2BUA), proxy, and translation services, as described below.

EPC virtualization stack 204 a serves as a core network proxy for communications between the RAN and the core network. Details regarding the core networks may be abstracted, translated, interworked, or otherwise changed, effectively virtualizing the core network to appear as a single, simplified core network to the RAN.

Radio virtualization stack 204 b serves as a RAN proxy for communications to/from the core network to/from the RAN. Similar to the operation of 204 a, details regarding the RAN sites may be abstracted, translated, interworked, or otherwise changed, and complexity is hidden from the core network by proxying and translating all communications from the core network. This may include masking all base station physical cell identities, tracking area codes, and other base station identifying information. From the core networks point of view, all of the RAN sites 201, 202 appear as a single base station or eNodeB. All handovers within the domain of the coordinating node are performed by the gateway, in some cases using an internal EPC functionality, and not exposed to the core network. The core network sees UE attach/detach and other service requests, but is freed from having to manage the eNodeBs themselves. According to the LTE standard, in addition to handover signaling, to prevent data loss during handover, indirect data tunnels are created by MME with source eNodeB, target eNodeB and at SGW. The coordinating node may also take care of indirect data tunneling as well, thus reducing the signaling between MME and SGW during handover.

Box 205 shows a heterogeneous mix of cores, as enabled to be used in conjunction with coordinating node 204. The heterogeneous mix of cores may include one core, two cores, or more cores. The heterogeneous mix of cores may include a dedicated core for Internet of Things (IoT) applications, or for any other applications. The heterogeneous mix of cores may include a plurality of cores managed by different administrative agencies or companies, or multiple cores managed by the same company. Although a single set of RAN nodes is not typically able to be shared among multiple cores, the use of EPC virtualization stack 204 a, as described above, permits the details of the core network to be abstracted or virtualized.

Core network(s) 205 are in communication with coordinating node 204 and also with operator networks 206, for example, via a packet gateway (PGW) to the public Internet.

Box 206 shows a number of networks, public and private, that may be connected to the one or more core networks 205, including an IP Multimedia Subsystem (IMS) network for providing mobile subscriber authentication and Voice over LTE (VoLTE) functionality, the public Internet, an enterprise private network, or an Internet of Things (IoT) network.

FIG. 3 is an exemplary call flow diagram showing improved paging. UE 301 is in communication with a network. In the network are radio access network nodes as follows: first femto access point 302, first Wi-Fi access point 303, second Wi-Fi access point 304, second femto access point 305. In the present disclosure, access point is understood to mean either access point or base station, or both, except where context makes its meaning unambiguous. Further towards the core network are a coordination server 306 (here identified as HNG, short for the Parallel Wireless HetNet Gateway™), a mobile switching center (MSC) or serving GPRS support node (SGSN) 307, and a packet data network gateway (PGW).

At step 309, the UE is in idle mode and is physically in the zone of Femto-AP1. The UE makes an RRC connection to Femto AP1 to complete a call, which registers with the PGW via the HNG. The HNG stores the UE's IMSI at step 310. When the call terminates, the UE is de-registered.

At step 311, the UE moves to the physical coverage area of Wi-FI AP 2. As Wi-Fi AP 2 is not a base station in the network, the AP sets up an IPsec tunnel to the HNG, which is acting as an ePDG to permit access to the core network. At this point, the HNG updates the UE IMSI/TMSI information, at step 312. The HNG is aware that Wi-Fi AP 2 and Femto AP 2 are the same zone. This is based on the understanding that Wi-Fi AP2 and Femto AP 2 are actually the same multi-RAT device, in some embodiments. This understanding of which multi-RAT base stations are capable of which RAT is based on an association at the HNG of each separate base station identifier (e.g., Wi-Fi AP 2 304 and Femto AP 2 305) with each others' cell identifiers, such as via ECGI. It is helpful to note that identifiers are RAT-specific, and thus by associating these RAT identifiers, the base station may be understood by the HNG 306 to have multiple RAT capabilities. In some embodiments, all RATs of a base station can be associated with one identifier. In some embodiments, all RAT identifiers of a base station may be associated with all other identifiers of that base station.

Following step 312, a data flow initiated by the P-GW causes data to be sent through the network to the UE. At step 313, the UE has camped on the Wi-Fi network of Wi-Fi AP 2 and this has been updated at step 312 in the location database at HNG 306.

Next, an incoming circuit-switched call is received at the core network, at step 314. The call is attempted to be completed by the 3G core network (here shown as MSC/SGSN 307). The 3G core node 307 sends a paging message with the UE's IMSI to the HNG 306, which performs a lookup based on the IMSI into a location database.

The location database may be any database known to one having skill in the art. The database may contain the UE's last known position, listed as a cell identifier such as an ECGI, or listed as geographic coordinates. The database may contain multiple UE identifiers, not limited just to IMSI but also extending to other UE identifiers as described herein. The database may be queried based on any of these identifiers to retrieve one or more of the associated locations of the UE.

At step 315, the location is searched and retrieved at the coordinating gateway. The updated IMSI mapping info is used to page the UE in femto AP 2. At step 316, broadcast paging occurs on the cell of femto AP 2 (305). This allows the base station to directly page the UE, at step 317, causing the UE to initiate an RRC connection and enabling the core network to complete the call.

FIG. 4 is a schematic diagram of a mesh network node, in accordance with some embodiments. Mesh network node 400 may include processor 402, processor memory 404 in communication with the processor, baseband processor 406, and baseband processor memory 408 in communication with the baseband processor. Mesh network node 400 may also include first radio transceiver 412 and second radio transceiver 414, internal universal serial bus (USB) port 416, and subscriber information module card (SIM card) 418 coupled to USB port 416. In some embodiments, the second radio transceiver 414 itself may be coupled to USB port 416, and communications from the baseband processor may be passed through USB port 416.

A mesh routing module 430 may also be included, and may be in communication with a configuration module 432, for handling routing tables, configuration messages from a cloud coordination server, and other configuration information. These modules may be software modules, processes, containers, or monolithic software processes. Configuration module 432 and mesh routing module 430 may each run on processor 402 or on another processor, or may be located within another device.

Processor 402 and baseband processor 406 are in communication with one another. Processor 402 may perform routing functions, and may determine if/when a switch in network configuration is needed. Baseband processor 406 may generate and receive radio signals for both radio transceivers 412 and 414, based on instructions from processor 402. In some embodiments, processors 402 and 406 may be on the same physical logic board. In other embodiments, they may be on separate logic boards.

The first radio transceiver 412 may be a radio transceiver capable of providing LTE eNodeB functionality, and may be capable of higher power and multi-channel OFDMA. The second radio transceiver 414 may be a radio transceiver capable of providing LTE UE functionality. Both transceivers 412 and 414 may be capable of receiving and transmitting on one or more LTE bands. In some embodiments, either or both of transceivers 412 and 414 may be capable of providing both LTE eNodeB and LTE UE functionality. Transceiver 412 may be coupled to processor 402 via a Peripheral Component Interconnect-Express (PCI-E) bus, and/or via a daughtercard. As transceiver 414 is for providing LTE UE functionality, in effect emulating a user equipment, it may be connected via the same or different PCI-E bus, or by a USB bus, and may also be coupled to SIM card 418. First transceiver 412 may be coupled to first radio frequency (RF) chain (filter, amplifier, antenna) 422, and second transceiver 414 may be coupled to second RF chain (filter, amplifier, antenna) 424.

SIM card 418 may provide information required for authenticating the simulated UE to the evolved packet core (EPC). When no access to an operator EPC is available, a local EPC may be used, or another local EPC on the network may be used. This information may be stored within the SIM card, and may include one or more of an international mobile equipment identity (IMEI), international mobile subscriber identity (IMSI), or other parameter needed to identify a UE. Special parameters may also be stored in the SIM card or provided by the processor during processing to identify to a target eNodeB that device 400 is not an ordinary UE but instead is a special UE for providing backhaul to device 400.

Wired backhaul or wireless backhaul may be used. Wired backhaul may be an Ethernet-based backhaul (including Gigabit Ethernet), or a fiber-optic backhaul connection, or a cable-based backhaul connection, in some embodiments. Additionally, wireless backhaul may be provided in addition to wireless transceivers 412 and 414, which may be Wi-Fi 802.11a/b/g/n/ac/ad/ah, Bluetooth, ZigBee, microwave (including line-of-sight microwave), or another wireless backhaul connection. Any of the wired and wireless connections described herein may be used flexibly for either access (providing a network connection to UEs) or backhaul (providing a mesh link or providing a link to a gateway or core network), according to identified network conditions and needs, and may be under the control of processor 402 for reconfiguration.

Other elements and/or modules may also be included, such as a home eNodeB, a local gateway (LGW), a self-organizing network (SON) module, or another module. Additional radio amplifiers, radio transceivers and/or wired network connections may also be included.

Processor 402 may identify the appropriate network configuration, and may perform routing of packets from one network interface to another accordingly. Processor 402 may use memory 404, in particular to store a routing table to be used for routing packets. Baseband processor 406 may perform operations to generate the radio frequency signals for transmission or retransmission by both transceivers 410 and 412. Baseband processor 406 may also perform operations to decode signals received by transceivers 412 and 414. Baseband processor 406 may use memory 408 to perform these tasks.

FIG. 5 is a schematic diagram of a routing coordination node, in accordance with some embodiments. Coordinator server 500 includes processor 502 and memory 504, which are configured to provide the functions described herein. Also present are radio access network coordination/routing (RAN Coordination and routing) module 506, including database 506 a, RAN configuration module 508, and RAN proxying module 510. In some embodiments, coordinator server 500 may coordinate multiple RANs using coordination module 506. In some embodiments, coordination server may also provide proxying, routing virtualization and RAN virtualization, via modules 510 and 508. In some embodiments, a downstream network interface 512 is provided for interfacing with the RANs, which may be a radio interface (e.g., LTE), and an upstream network interface 514 is provided for interfacing with the core network, which may be either a radio interface (e.g., LTE) or a wired interface (e.g., Ethernet).

Coordinator 500 includes local evolved packet core (EPC) module 520, for authenticating users, storing and caching priority profile information, and performing other EPC-dependent functions when no backhaul link is available. Local EPC 520 may include local HSS 522, local MME 524, local SGW 526, and local PGW 528, as well as other modules. Local EPC 520 may incorporate these modules as software modules, processes, or containers. Local EPC 520 may alternatively incorporate these modules as a small number of monolithic software processes. Modules 506, 508, 510 and local EPC 520 may each run on processor 502 or on another processor, or may be located within another device.

In any of the scenarios described herein, where processing may be performed at the cell, the processing may also be performed in coordination with a cloud coordination server. A mesh node may be an eNodeB. An eNodeB may be in communication with the cloud coordination server via an X2 protocol connection, or another connection. The eNodeB may perform inter-cell coordination via the cloud communication server, when other cells are in communication with the cloud coordination server. The eNodeB may communicate with the cloud coordination server to determine whether the UE has the ability to support a handover to Wi-Fi, e.g., in a heterogeneous network.

Although IMSI is described in some embodiments, other equipment identifiers could be used, in conjunction with IMSI or independently, in some embodiments. For example, TMSI, T-TMSI, S-TMSI, MMEI, IMEI, MEID, GUTI, WLAN MAC addresses, SIM ICCID, hardware serial numbers, or other identifiers could be used in conjunction with IMSI or independently. In some embodiments, when a single device is known to be on more than one RAT, all identifiers used by that device may be associated in the database described herein, and translation between identifiers may be performed when performing inter-RAT handling, in some embodiments. For example, this may be performed to enable tracking and/or paging across RATs. 2G is also contemplated as part of this disclosure.

In some embodiments, when there is Paging Request from one RAT, it has to be forwarded using that RAT only. I.e., if there is 3G paging, it can be forwarded to CWS using the same 3G RAN technology.

Although certain types of cell identifiers are described in some embodiments, other cell identifiers could be used, in conjunction or independently, in some embodiments. For example, ECGI (4G) and cell ID (3G) could be used as multi-RAT cell identifiers that identify across multiple RATs. Certain identifiers may be used as multi-RAT cell identifiers, which can identify a cell or base station across multiple RATs. In some embodiments a list or database may be maintained so that the coordinating gateway is aware which base stations are capable of which RATs, and this may be used for various purposes. One such purpose could be to send a paging message to a particular base station in the same RAT as the originally originated paging message.

Although small cell base stations are described in some embodiments, any power cells could be used in other embodiments. For example, femto cells or macro cells could be used with the disclosed invention. Mesh base stations could be used, in some embodiments, or other cells with shared backhaul, as described by U.S. Pat. Pub. No. US20140233412, hereby incorporated by reference in its entirety. In the present disclosure, the term radio access network is used to describe the cell, base station, or access point that provides access, e.g., a base station such as an eNodeB, or a Wi-Fi AP, or a multi-RAT base station capable of more than one RAT.

Although the methods above are described as separate embodiments, one of skill in the art would understand that it would be possible and desirable to combine several of the above methods into a single embodiment, or to combine disparate methods into a single embodiment. For example, all of the above methods could be combined. In the scenarios where multiple embodiments are described, the methods could be combined in sequential order, or in various orders as necessary.

Although the above systems and methods for providing interference mitigation are described in reference to the Long Term Evolution (LTE) standard, one of skill in the art would understand that these systems and methods could be adapted for use with other wireless standards or versions thereof. For example, certain methods involving the use of a virtual cell ID are understood to require UEs supporting 3GPP Release 11, whereas other methods and aspects do not require 3GPP Release 11.

In some embodiments, the software needed for implementing the methods and procedures described herein may be implemented in a high level procedural or an object-oriented language such as C, C++, C#, Python, Java, or Perl. The software may also be implemented in assembly language if desired. Packet processing implemented in a network device can include any processing determined by the context. For example, packet processing may involve high-level data link control (HDLC) framing, header compression, and/or encryption. In some embodiments, software that, when executed, causes a device to perform the methods described herein may be stored on a computer-readable medium such as read-only memory (ROM), programmable-read-only memory (PROM), electrically erasable programmable-read-only memory (EEPROM), flash memory, or a magnetic disk that is readable by a general or special purpose-processing unit to perform the processes described in this document. The processors can include any microprocessor (single or multiple core), system on chip (SoC), microcontroller, digital signal processor (DSP), graphics processing unit (GPU), or any other integrated circuit capable of processing instructions such as an x86 microprocessor.

The foregoing discussion discloses and describes merely exemplary embodiments of the present invention. In some embodiments, software that, when executed, causes a device to perform the methods described herein may be stored on a computer-readable medium such as a computer memory storage device, a hard disk, a flash drive, an optical disc, or the like. As will be understood by those skilled in the art, the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. For example, wireless network topology can also apply to wired networks, optical networks, and the like. The methods may apply to 2G networks, LTE-compatible networks such as 5G, to UMTS-compatible networks, or to networks for additional protocols that utilize radio frequency data transmission. Various components in the devices described herein may be added, removed, split across different devices, combined onto a single device, or substituted with those having the same or similar functionality.

Although the present disclosure has been described and illustrated in the foregoing example embodiments, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the details of implementation of the disclosure may be made without departing from the spirit and scope of the disclosure, which is limited only by the claims which follow. Various components in the devices described herein may be added, removed, or substituted with those having the same or similar functionality. Various steps as described in the figures and specification may be added or removed from the processes described herein, and the steps described may be performed in an alternative order, consistent with the spirit of the invention. Features of one embodiment may be used in another embodiment. Other embodiments are within the following claims. 

1. A method, comprising: providing a combined user device location database in a heterogeneous radio access network at a coordinating gateway between a plurality of radio access network nodes and a plurality of core network nodes; at the coordinating gateway, storing a first location of a user device in the combined user device location database in association with a user device identifier and based on receiving a first user device registration request at a first radio access network; at the coordinating gateway, storing a second location of the user device in the combined user device location database in association with the user device identifier and based on receiving a second user device registration request at a second radio access network; and querying the combined user device location database for a last known location of the user device across both the first and the second radio access network, thereby maintaining a combined user device location database across multiple radio access technologies in a heterogeneous radio access network.
 2. The method of claim 1, wherein the user device is a UE, and wherein the user device identifier is an international mobile subscriber identity (IMSI).
 3. The method of claim 1, wherein the first and second radio access network provide access via different radio access technologies.
 4. The method of claim 1, further comprising sending a paging request to the user device via the first radio access network based on the last known location.
 5. The method of claim 1, further comprising receiving a paging request to the user device using a first radio access technology of the first radio access network.
 6. The method of claim 1, further comprising recording an international mobile subscriber identity (IMSI) of the user device at the coordinating gateway from both the first and the second received user device registration requests.
 7. The method of claim 1, wherein the coordinating gateway is an evolved packet data gateway (ePDG) or trusted wireless access gateway (TWAG), and wherein the method further comprises recording an international mobile subscriber identity (IMSI) of the user device upon IPsec security tunnel establishment for the user device at the coordinating gateway.
 8. The method of claim 1, wherein the coordinating gateway is an evolved packet data gateway (ePDG) or trusted wireless access gateway (TWAG), and wherein the coordinating gateway is a gateway between the plurality of radio access network nodes and a Long Term Evolution (LTE) packet data network gateway (PGW), and wherein the coordinating gateway is a gateway between the plurality of radio access network nodes and a serving global packet radio service support node (SGSN).
 9. The method of claim 1, further comprising receiving an incoming paging request for a first radio access technology, and based on the queried last known location, preferentially sending a paging request to a multi-radio access technology base station.
 10. The method of claim 1, wherein the first location and the second location are base station identifiers.
 11. The method of claim 1, wherein the first location is an identifier of the first radio access network and the second location is an identifier of the second radio access network, and wherein the first location and the second location are E-UTRAN cell global identifiers (ECGIs).
 12. The method of claim 1, further comprising storing position coordinates of the user device in the combined user device location database, retrieving the stored position coordinates of the user device as a result to a query to the combined user location database for the last known location of the user device, and sending paging messages to base stations in a geographical region based on the retrieved stored position coordinates.
 13. A system for providing paging in a cellular telecommunications network, comprising: a first multi-radio access technology (multi-RAT) base station; a second multi-RAT base station in communication with the first multi-RAT base station; and a coordinating gateway in communication with the first and second multi-RAT base stations and situated between the first and second multi-RAT base stations and a core network, the coordinating gateway further comprising: a combined user device location database, and a processing module configured to perform steps including: providing a combined user device location database in a heterogeneous radio access network at the coordinating gateway between the first and second multi-RAT base stations and a plurality of core network nodes; at the coordinating gateway, storing a first location of a user device based on receiving a first user device registration request at the first multi-RAT base station; at the coordinating gateway, storing a second location of the user device based on receiving a second user device registration request at the second multi-RAT base station; and querying the combined user device location database for a last known location of the user device across both the first and the second multi-RAT base stations, thereby maintaining a combined user device location database across multiple radio access technologies in a heterogeneous radio access network. 